add FashionMnist

.github/ISSUE_TEMPLATE.md

@@ -8,7 +8,7 @@ Feature Requests:
 2. Add a new feature. Please note that, you can implement a lot of features by extending tensorpack
 	(See http://tensorpack.readthedocs.io/en/latest/tutorial/index.html#extend-tensorpack).
 	It may not have to be added to tensorpack unless you have a good reason.
-3. Note that we don't take "example requests".
+3. Note that we don't implement papers at other's requests.
 
 Usage Questions:
 Usage questions are like "How do I do [this specific thing] in tensorpack?".

tensorpack/dataflow/dataset/mnist.py

@@ -12,17 +12,16 @@ from ...utils import logger
 from ...utils.fs import download, get_dataset_path
 from ..base import RNGDataFlow
 
-__all__ = ['Mnist']
+__all__ = ['Mnist', 'FashionMnist']
 
-SOURCE_URL = 'http://yann.lecun.com/exdb/mnist/'
 
-
-def maybe_download(filename, work_directory):
+def maybe_download(url, work_directory):
     """Download the data from Yann's website, unless it's already here."""
+    filename = url.split('/')[-1]
     filepath = os.path.join(work_directory, filename)
     if not os.path.exists(filepath):
-        logger.info("Downloading mnist data to {}...".format(filepath))
-        download(SOURCE_URL + filename, work_directory)
+        logger.info("Downloading to {}...".format(filepath))
+        download(url, work_directory)
     return filepath
 
 
@@ -69,6 +68,9 @@ class Mnist(RNGDataFlow):
     image is 28x28 in the range [0,1], label is an int.
     """
 
+    DIR_NAME = 'mnist_data'
+    SOURCE_URL = 'http://yann.lecun.com/exdb/mnist/'
+
     def __init__(self, train_or_test, shuffle=True, dir=None):
         """
         Args:
@@ -76,15 +78,15 @@ class Mnist(RNGDataFlow):
             shuffle (bool): shuffle the dataset
         """
         if dir is None:
-            dir = get_dataset_path('mnist_data')
+            dir = get_dataset_path(self.DIR_NAME)
         assert train_or_test in ['train', 'test']
         self.train_or_test = train_or_test
         self.shuffle = shuffle
 
         def get_images_and_labels(image_file, label_file):
-            f = maybe_download(image_file, dir)
+            f = maybe_download(self.SOURCE_URL + image_file, dir)
             images = extract_images(f)
-            f = maybe_download(label_file, dir)
+            f = maybe_download(self.SOURCE_URL + label_file, dir)
             labels = extract_labels(f)
             assert images.shape[0] == labels.shape[0]
             return images, labels
@@ -111,6 +113,11 @@ class Mnist(RNGDataFlow):
             yield [img, label]
 
 
+class FashionMnist(Mnist):
+    DIR_NAME = 'fashion_mnist_data'
+    SOURCE_URL = 'http://fashion-mnist.s3-website.eu-central-1.amazonaws.com/'
+
+
 if __name__ == '__main__':
     ds = Mnist('train')
     for (img, label) in ds.get_data():